1. Field of the invention
The present invention relates to a vehicle suspension mechanism, more particularly to a strut suspension mechanism for controlling a camber angle of a vehicle wheel in accordance with vehicle driving condition.
2. Description of the Prior Art
There has been proposed a vehicle suspension mechanism constituted so as to produce a certain change in the camber angle of the vehicle wheel during a cornering operation of the vehicle.
Japanese Patent Public Disclosure No. 61-64506, laid open to the public on Apr. 2, 1986, corresponding to European Patent Publication No. 174,007 discloses a strut suspension mechanism in which an upper end of a piston rod of a strut assembly is connected with a vehicle body through an assist link and a lower end of the strut assembly is connected with a vehicle wheel through a ball joint, a knuckle and the like.
With this structure, in the case where an outer side wheel of the vehicle displaces upwardly relative to the vehicle body when the vehicle is running on a curved path, or the vehicle is in a cornering operation, the strut assembly is urged upwardly so that the upper end of the piston rod of the strut assembly is displaced upwardly and inwardly by means of the assist link. In other words, the upper end of the strut assembly is displaced in a direction oblique to the longitudinal axis of the piston rod so that the strut assembly pivots slightly to the inside about the lower end. This causes pivotal inclination of the vertical axis of the wheel slightly inwardly to produce a negative change in the camber angle of the wheel.
This negative camber angle change during the cornering operation of the vehicle is effected to provide the vehicle with a running stability.
It should be however noted that in the strut suspension disclosed in the Japanese Patent Public Disclosure No. 61-64506, the piston rod of the strut assembly produces a upward displacement in the direction of the longitudinal axis of the piston rod even where one of the wheels climbs a projection on a road during running a straight path as well. This causes the assist link to displace the upper end of the strut assembly in a direction oblique to the longitudinal axis of the piston rod resulting in a negative camber angle change. This means that the strut suspension structure disclosed the Japanese Patent application may produce a negative change in the camber angle of the wheel during a straight driving condition of the vehicle so that the driving stability of the vehicle is deteriorated when the vehicle runs in a straight path.